Mario, thank you very much for your really very interesting letter and not long for me.
I had doubts about planetary hours because it is easy to prove that a shadow casted by a horizontal or vertical gnomon do not move equally with a local hour angle, except from the low latitudes for horizontal gnomon or high latitudes for vertical one where the difference is small. So when I saw, let me call them, primitive dials it always seemed doubtful for me how they can indicate hours which are equal in one day. About "ecclesiastical sundials". There are also some examples in Poland but next question arises. Why there are so concentrated in England much more than in any other country. Also thank you very much for pointing references though I am afraid it is not so easy for me to obtain them. Best regards Krzysztof Kotynia
